JP2001006923A - Magnetic marker for controlling running of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a magnetic marker to be easily laid on a road and to increase the magnetic field intensity of the marker at a distant position from the surface of the road as a whole, and, in addition, to make magnetic nails, etc., hardly stand upright on the marker by using a flat magnet having a recessed section or hole section at a needed spot on the surface. SOLUTION: At the central part of a discoid flat magnet which is laid on a road as a magnetic marker, one cylindrical recessed section 1 having a relatively large size is provided. At the central part of a square flat magnet, alternatively, one square hole section 2 having a relatively large size is provided. The recessed section 1 or hole section 2 is provided at the central part of the magnet where the magnetic flux density on the surface of the magnet decreases so as to increase the magnetic field intensity above the surface of the magnet. In addition, nails, etc., are made to hardly stand upright on the magnet even when the nails, etc., are magnetized so as to prevent tires from getting punctured. Moreover, the magnet is reinforced by filling up the recessed section 1 or hole section 2 with a nonmagnetic material. Therefore, the magnet can be laid easily on a road and extremely reduces the wandering of automobiles on their target running lines.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for easily laying a magnet on a road, obtaining a high magnetic field strength at a position distant from a road on which a magnet is laid, and standing up a magnetic nail or the like on a road on which a magnet is laid. The present invention relates to a magnetic marker for vehicle running control that is difficult to perform.

[0002]

2. Description of the Related Art In a magnetic induction system for a vehicle, a magnetic target is formed by continuously arranging a number of magnetic markers at intervals of about 1 m in a longitudinal direction of a road to form a traveling target line. When the running vehicle deviates from the target line by a certain distance, a magnetic sensor on the bottom surface of the vehicle detects this and automatically corrects the running direction of the vehicle. Therefore, the magnetic marker is required to have a high magnetic field strength about 30 cm above the road surface on which the automobile passes. The magnetic marker has, for example, a diameter of 100 to 120 as shown in FIG.
Disc-shaped flat magnets 8 having a thickness of about 4 mm to 6 mm have been proposed.

[0003]

The conventional flat magnet 8 described above.
Although it is flat, it is easy to lay it, but not only is it not possible to obtain a sufficient magnetic field strength, but also there are problems that nails and the like scattered on the road easily stand upright and cause puncture. In particular, if the front wheels are punctured, the steering wheel operation may be affected, leading to a major accident. In view of this, the present inventor has conducted various studies. As a result, the conventional flat magnet has a low magnetic flux density at the central portion thereof. We found that the magnetic flux density in the surroundings was high, the magnetic field strength at a position about 30 cm away from the magnet was high overall, and it was difficult for e.g. magnetic nails to stand upright. It led to.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a magnetic marker for vehicle running control which is easy to lay, has a high magnetic field strength at a position distant from a road surface, and hardly causes a magnetic nail or the like to stand upright.

[0004]

According to the first aspect of the present invention,
This is a magnetic marker for vehicle running control, wherein a flat magnet having a concave portion or a hole at a required position on the surface is used.

According to a second aspect of the present invention, the cross section of the recess or the hole is a circle, an ellipse, a triangle, a quadrangle, or a polygon having a pentagon or more.
It is a magnetic marker for vehicle running control of the description.

According to a third aspect of the present invention, there is provided the magnetic marker for vehicle running control according to the first aspect, wherein the recess or the hole has a linear shape or an arc shape.

According to a fourth aspect of the present invention, there is provided the magnetic marker for controlling a vehicle running according to the third aspect, wherein the flat magnet has a disk shape, and a concave portion or a hole portion is provided concentrically. is there.

According to a fifth aspect of the present invention, the concave portion or the hole portion is filled with a non-magnetic material.
A magnetic marker for vehicle running control according to any one of 2, 3, and 4.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a place where a concave portion or a hole is provided is a central portion (excluding an edge portion) on the flat magnet surface where the magnetic flux density is reduced. The cross section of the concave portion or the hole portion may be any shape such as a circle, an ellipse, a triangle, a quadrangle, a polygon having a pentagon or more, a straight line, and an arc.

An embodiment of a flat magnet used in the present invention will be specifically described below with reference to the drawings. The flat magnet (first embodiment) shown in FIG. 1A has a relatively large cylindrical recess 1 in the center of a disk-shaped flat magnet. The flat magnet (second embodiment) shown in FIG. 1 (b) is one in which one square hole 2 having a relatively large size is provided at the center of a square plate-shaped flat magnet. The flat magnet (third embodiment) shown in FIG. 2A has a ring-shaped recessed portion 3 provided concentrically in the middle of a disk-shaped flat magnet. The flat magnet (fourth embodiment) shown in FIG.
The plurality of arc-shaped holes 4 are provided concentrically and one by one. The flat magnet (fifth embodiment) shown in FIG.
Three arc-shaped holes 4 are provided concentrically and doubly in an intermediate portion of a disk-shaped flat magnet. The flat magnet (sixth embodiment) shown in FIG. 3A has a large number of columnar recesses 5 provided in the center of a disk-shaped flat magnet. FIG.
The flat magnet (7th embodiment) shown in (b) has a large number of cylindrical holes 6 provided in the center of a disk-shaped flat magnet. The flat magnet (eighth embodiment) shown in FIG.
A large number of linear holes 7 are provided in parallel at the center of a flat rectangular plate-shaped magnet.

In the present invention, if a concave portion or a hole is provided on the surface of the flat magnet, the magnetic field strength is increased as a whole because the demagnetizing field decreases near the concave portion or the hole, and as a result, It is considered that the magnetic flux density increases. In addition, it is considered that the nail or the like is difficult to stand upright even when magnetized on the magnetic marker (flat magnet) of the present invention, probably because the demagnetizing field in the central portion where the concave portion or the hole is provided becomes small. . In particular, it is difficult to stand upright when there is one recess or hole at the center of the flat magnet (see FIG. 1).

In the present invention, the maximum diameter L or the longest side h of the cylindrical or prismatic concave portion or the hole, the width p of the ring-shaped concave portion, the arc-shaped concave portion or the hole, and the width t of the linear hole are described.
Is the thickness T of the flat magnet (L, h, p, t,
T is preferably about 1 to 8 times that of FIGS.
If it is less than twice, the effect of improving the magnetic flux density cannot be obtained sufficiently,
If it exceeds twice, the effect is saturated. Further, the total area of the cross section of the recess or the hole is preferably about 3 to 50% of the area of the surface of the flat magnet (one side area), and if it is less than 3%, the effect is not sufficiently obtained. If it exceeds, the effect is saturated, and the flat magnet has a reduced strength and is easily broken.

In the present invention, the material of the flat magnet is arbitrary, such as plastic mag (plastic magnet) and rubber mag (rubber magnet). The shape of the flat magnet is arbitrary such as a disk shape or a square plate shape. The flat magnet is made of ferrite or Nd-Fe
It can be easily manufactured by press-forming or roll-forming a mixture obtained by kneading magnetic powder such as -B type with plastic powder or rubber powder.

In the present invention, the concave portion may be provided on both the front and back surfaces of the flat magnet, or the concave portion and the hole may coexist. If the concave portion is too shallow, the effect cannot be sufficiently obtained. Therefore, it is desirable that the concave portion is set to at least 1/2 of the thickness of the flat magnet.

In the present invention, a disk-shaped flat magnet in which a ring-shaped concave portion is provided concentrically at a required position on the surface or an arc-shaped hole portion which is provided concentrically (see FIG. 2) has a low magnetic field strength. It is desirable that there is no anisotropy and the position recognition as a magnetic marker is high.

In the flat magnet used in the present invention, since the corners of the concave portions or the holes may be damaged during use, it is preferable to reinforce the concave portions or the holes by filling them with a non-magnetic material. Although any material can be used for the non-magnetic material, when the flat magnet is a plastic magnet, a plastic material of the same material as that used therein, and when the flat magnet is a rubber mug, it is used there. It is desirable to use a rubber material of the same material as the above.

In the present invention, the flat magnet is Nd-Fe-
In the case of a material that is easily corroded, such as a B-based material, it is preferable to use a resin coated resin. In the case of a hardly corrosive material such as ferrite, it can be used as it is.

Since the magnetic marker (flat magnet) of the present invention is flat, it can be laid on the road surface. For laying on the road surface, gluing or nailing can be used. Also, when buried under the road surface, it is not necessary to excavate deeply, and the laying can be easily performed. The flat magnet has any shape such as a circle, an ellipse, and a polygon, and has a thickness of about 4 to 10 mm and a surface dimension of about 80 to 200 mm in terms of a circle when converted to a circle.

[0019]

The present invention will be described below in detail with reference to examples. (Example 1) The surface of a ferrite magnet powder was surface-treated with a 2 wt% titanate coupling agent, PPS (polyphenylene sulfide) was added to the surface, and the mixture was kneaded. (B) (b), FIG.
(A) to (c) and flat magnets made of ferrite rubber mugs having the shapes shown in FIGS. 3 (a) to (c) were manufactured. The content of the magnet powder was all 50% by volume. Fig. 1 (a), Fig. 2
The dimensions of the flat magnets shown in (a) to (c) and FIGS. 3 (a) and (b) are 200 mm in diameter, 6 mm in thickness, and FIGS.
The dimensions of the flat magnet shown in (c) are 170 mm square, and the thickness is 6 mm.
mm. The recesses or holes shown in FIGS. 3A and 3B are circular in cross section and have a diameter of 3.0 mm.

Comparative Example 1 A conventional ferrite rubber mug flat magnet (diameter 200 mm, thickness 6) having the shape shown in FIG.
mm) 8 was press-molded in the same manner as in Example 1.

For each of the flat magnets obtained in Example 1 and Comparative Example 1, the magnetic field intensity immediately above 300 mm was measured.
Table 1 shows the results. The positions, depths, widths, and the like of the recesses or holes are also shown in Table 1. When the ring-shaped recess or arc-shaped hole is provided concentrically (Fig. 2 (a)-
The position of the concave portion or the hole of (c) is shown by the distance from the center point of the flat magnet to the center line of the concave portion or the hole.

[0022]

[Table 1] (Note) * Position: distance from the center of the flat magnet, depth: recess depth, area ratio: ratio to the area of the flat magnet (%). Nos. 6 and 7 are within a circle with a diameter of 70 mm concentric with the flat magnet, and No. 8 are within a square with a side of 70 mm concentric with the flat magnet.

As is clear from Table 1, No. 1 of the present invention example
8 showed a magnetic field strength higher than that of the conventional product (No. 9) by 20% or more. This is because a magnetic flux density is increased by providing a concave portion or a hole in a low magnetic flux density portion at the center of the surface of the flat magnet.

(Example 2) No. 1 of the present invention shown in Table 1
-8, a large number of No. 9 flat magnets (magnetic markers) of the comparative example are embedded at intervals of 1 m at a position 50 mm below the road surface to form nine types of travel target lines. The vehicle was mounted with a magnetic sensor (a fluxgate sensor having a magnetic flux resolution of 0.01 G) mounted on the bottom surface of the vehicle, and the lateral fluctuation of the vehicle was measured.

As a result, in each of the lines using the flat magnets No. 1 to No. 8 of the present invention as the magnetic markers, the wobble of the automobile was extremely small at 30 to 35 mm on one of the left and right sides. It was recognized that the wobble tended to decrease as the magnetic field intensity increased. On the other hand, in the line using No. 9 of the comparative example as the magnetic marker, the wobble of the automobile was as large as 45 mm on one of the left and right sides.

(Embodiment 3) Nail of various sizes were scattered on each of the nine kinds of traveling target lines used in Embodiment 2, and the magnetization state was observed. In the magnetic markers of Nos. 1 and 2 of the present invention,
No nail of any size was upright. No.3 ~ 8
In the case of the magnetic marker described above, a short nail having a length of about 3 to 5 mm, which cannot be a cause of puncture, was erected, but a longer nail than that was not erected. On the other hand, in the conventional magnetic marker (No. 9), it was confirmed that nails up to 30 mm in length could be upright and cause puncture.

[0027]

As described above, since the magnetic marker of the present invention uses a flat magnet, it can be easily installed on a road.
Further, since the flat magnet is provided with a concave portion or a hole at a required portion except for an edge on the surface thereof, the magnetic field strength above the flat magnet surface is high, and the traveling target line using this as a magnetic marker is used for a vehicle. The wobble becomes extremely small. Also, nails magnetized on the magnetic marker of the present invention are unlikely to stand upright and are less likely to cause punctures. Therefore, an industrially remarkable effect is achieved.

[Brief description of the drawings]

FIGS. 1 (a) and 1 (b) are a plan view and a side perspective view, respectively, showing first and second embodiments of a flat magnet used in the present invention.

FIGS. 2A to 2C are a plan view and a side perspective view, respectively, showing third to fifth embodiments of the flat magnet used in the present invention.

FIGS. 3A to 3C are a plan view and a side perspective view, respectively, showing sixth to eighth embodiments of the flat magnet used in the present invention.

FIG. 4 is a plan view and a side perspective view of a conventional flat magnet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical recess with relatively large size 2 Square-shaped hole with relatively large size 3 Ring-shaped recess 4 Arc-shaped hole 5 Cylindrical recess 6 Cylindrical hole 7 Linear hole 8 Conventional flat magnet

Claims (5)

[Claims] 1. A magnetic marker for vehicle running control, wherein a flat magnet having a concave portion or a hole at a required position on a surface is used. 2. The magnetic marker for vehicle running control according to claim 1, wherein the cross section of the recess or the hole is a circle, an ellipse, a triangle, a quadrangle, or a polygon having a pentagon or more. 3. The magnetic marker for vehicle running control according to claim 1, wherein the recess or the hole has a linear shape or an arc shape. 4. The magnetic marker for vehicle running control according to claim 3, wherein the flat magnet has a disk shape, and a concave portion or a hole portion is provided concentrically. 5. The magnetic marker for vehicle running control according to claim 1, wherein the recess or the hole is filled with a non-magnetic material.